Editing the Firefox Dictionary

One of my favorite features of Firefox is the built-in spellchecker. If you’re typing some text into a form (like posting on a message board or typing up an email on a web-based service), you’ll see a squiggly red line under any misspelled words. All you have to do is right-click the word and choose the correct spelling.

Unfortunately, the design of the context menu is such that it’s very easy to accidentally click “Add to Dictionary” when you try to correct a misspelled word. So you can accidentally add “teh” to your dictionary. What’s more, Firefox doesn’t have any way to edit the dictionary through the Firefox UI. So if you accidentally add “teh” to your dictionary, there’s no obvious way to remove it.

But there is, of course, a way… and here it is:

1) Close Firefox (you’ll probably want to open Task Manager and make sure that FIREFOX.EXE is no longer running, as it can take a few minutes to completely exit on your system).

2) Windows XP and Vista users should then click on Start > Run and type (or cut and paste) the following text into the “Run:” box:

%appdata%\Mozilla\Firefox\Profiles

3) In the Windows Explorer window that opens, you should see at least one folder with a name like “43y0xpxd.default” (the exact name will vary). Double-click this folder to open it.

If you have more than one folder with such a name, then you have more than one Firefox profile on your system. Open each folder and look at the “Date Modified” attribute for the BOOKMARKS.HTML file, as this might help you figure out which profile is the “correct” one.

4) Look for a file called PERSDICT.DAT and open it with your favorite text editor (Notepad is installed by default in all flavors of Windows, but I prefer Notepad++).

5) Remove the word you accidentally added to the dictionary, making sure that each word is on its own line.

6) Save the file and exit the editor.

7) Restart Firefox.

8) Rejoice that “teh” is now marked as a misspelled word again!

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